How to Sideboard on the Fly

The time between games is perhaps the most important point during a match of Magic. It’s when some of the most critical decisions are made—decisions that often alter the outcome of the match. How you sideboard is important, but figuring out how to sideboard can often be difficult. Thankfully however it’s also a decision that is easy to prepare for, because you know beforehand that it’s going to come up. This is all well and good, but what should we do when playing against a deck we’re unfamiliar with? Especially in a format as diverse as Legacy this scenario does tend to come up relatively often. And this is why we need to learn how to sideboard on the fly.

Before the game: Preparation

The first thing we should look for when it comes to sideboarding on the fly is how we can avoid it. The more you play a format the more familiar with it you’ll become. The more experienced you are the rarer it is for you to come across a deck that you’re completely unfamiliar with. Sure, few players have an intimate understanding of how a deck like, for example, Doomsday works. But experienced Legacy players have played against it enough to have a general idea of how the matchup usually plays out. More than that however, players who know more about Magic have a deeper and more nuanced understanding of the game, and can apply what they know about the game when making these decisions, even if they happen to lack a specific piece of format-specific knowledge.

Playing against more decks is a good way to prepare you have the time, but simply keeping up with content can help you be more prepared. Keeping an eye on tournament results, forum discussions, and deck techs are excellent ways to make sure you have a sufficient level of familiarity with the format. When preparing for a specific event you’ll generally be better served by focusing your attention on the top decks, but in the long term it pays to have a broader knowledge of the format.

Another way to prepare is to be mindful of this when building your deck, particularly when constructing the sideboard. Sideboarding on the fly is not always about knowing what cards are good in a certain matchup. You also need to have access to those cards. Generic answers have applications in more matchups, but narrow cards are often played precisely because of how good they are against specific, popular decks. This is a tradeoff that you should be aware of when deciding which cards to include in your sideboard, and which answer is the correct one is going to depend on the circumstances under which it is made. Would you rather have access to Marsh Casualties or Dread of Night?

During the game: Decision making

All too often we don’t give enough thought to how we ought to sideboard until we actually come up against a deck we haven’t played against before. Once you’re in the game, the time for preparation is over. You must focus instead on making the best decisions possible even with limited information. The first thing you should look for in a deck you’re unfamiliar with is similarities to other decks against which you do know how to sideboard.

By drawing parallels between similar decks, you will gain a rough idea of what you should and shouldn’t do. Even if you haven’t played against this particular deck before, you have most likely played against decks that are like it in some way. You’ve played against combo decks, control decks, decks with Stoneforge Mystic etc. before, and you have devised strategies for beating them. This is easier for experienced players, as they can often make comparisons to decks that more closely resemble what it is that they’re currently playing against, and serves to reiterate the importance of having a deeper and a broader knowledge of the game.

Try to figure out what the matchup is about, with regards to both strategy (card advantage, tempo etc.) and tactics (key cards). Which cards in your deck match up well against what your opponent is doing? And what cards in your opponent’s deck are important enough that they demand an answer even if that answer isn’t particularly useful against the rest of the deck? If your opponent is all in on Monastery Mentor it might be worth it to bring in a card like Toxic Deluge, even if their deck is otherwise creature light.

When in doubt, trust in the strength of your maindeck game plan. Don’t dilute your deck by bringing in too many cards that do nothing to further that plan. Unless you know that your plan A absolutely isn’t going to cut it, it’s usually better to let your deck do what it does best. This is especially true for proactive and synergistic decks that rely on a lot of their cards doing similar things or filling a specific purpose. If you’re a Storm player and you’re unsure what cards your opponent is going to bring in to fight you, focus on getting them dead with Tendrils of Agony as consistently as possible. Cabal Therapy can solve most problems preemptively—pay attention to their problem cards in game one—and you have enough cantrips to dig for your one Chain of Vapor should you need it. Don’t overdo it.

Notice that I still mention sideboarding a card like Chain of Vapor if you suspect it could be needed. There are some cards that are near unbeatable for certain decks if they cannot be answered, and most decks in Legacy have enough library manipulation that it’s probably worth it to hedge a little bit and play it safe if you think your opponent might be playing such a card. These cards often come in the form of noncreature permanents that many decks aren’t naturally equipped to deal with. Chalice of the Void, Ensnaring Bridge, and Grafdigger’s Cage are all cards that can practically win the game on the spot for your opponent if you decided to leave all of your answers in the sideboard.

Last but not least, pay attention to their mana base. The lands your opponent plays can tell you a lot about their deck, and also provide information that is absolutely crucial to determining whether you ought to bring in a card like Choke or Blood Moon. Conversely, if they play a ton of non-basics, they probably don’t have Blood Moon in their sideboard, if you’re worried about such things. If you focus only on what spells they play and forget to pay attention to their lands you will miss out on useful information.

After the game: Reflection

Once the game is finished, pay attention to how things played out. Can you identify what worked and what didn’t? Why you won or why you lost? It’s easy to just forget about it and move on—especially after a win—but it’s important to take the time to reflect on what we’ve learned if we wish to grow as players. Every match of Magic that you play is a potential source of valuable feedback. Use it.

If you do this enough times, you start learning how to sideboard on the fly—you experience what works, and what doesn’t. You might even enjoy it. In fact, some Legacy players love figuring out how to sideboard against a deck they’ve never seen before. There are a lot of random powerful cards out there in the long history of Magic: the Gathering. Someone is going to play them against you, and they won’t tell you in advance.

Sandro is a Magic player from Stockholm, Sweden. He’s been playing Goblins in Legacy for years. Follow him on Twitter @SandroRajalin